Method and apparatus for performing minimally invasive arthroscopic procedures

ABSTRACT

A surgical device capable of interconnecting to an external motorized hand pieces, bending a distal end segment, rotating a window element positioned distal to the distal end segment and rotating independently of it, and actuating a cutting element positioned within the outer window element and rotating independently of it.

REFERENCE TO PENDING PRIOR PATENT APPLICATIONS

This patent application is a continuation-in-part of pending prior U.S.patent application Ser. No. 14/224,897, filed Mar. 25, 2014 by GlenJorgensen et al. for METHOD AND DEVICES FOR MINIMALLY INVASIVEARTHROSCOPIC PROCEDURES (Attorney's Docket No. JORGEN-77251.000004 CON),which patent application is a continuation of prior U.S. patentapplication Ser. No. 12/399,471, filed Mar. 6, 2009 by Glen Jorgensen etal. for METHOD AND DEVICES FOR MINIMALLY INVASIVE ARTHROSCOPICPROCEDURES (Attorney's Docket No. JORGEN-77251.000004), which is acontinuation-in-part of prior U.S. patent application Ser. No.12/119,799, filed May 13, 2008 by Glen Jorgensen for METHOD AND DEVICESFOR MINIMALLY INVASIVE ARTHROSCOPIC PROCEDURES (Attorney's Docket No.JORGEN-77251.000008), which is a continuation of prior U.S. patentapplication Ser. No. 11/643,740, filed Dec. 20, 2006 by Glen Jorgensenfor METHOD AND DEVICES FOR MINIMALLY INVASIVE ARTHROSCOPIC PROCEDURES(Attorney's Docket No. JORGEN-77251.000011), which claims benefit ofprior U.S. Provisional Patent Application Ser. No. 60/752,284, filedDec. 20, 2005 by Glen Jorgensen for METHOD AND DEVICES FOR MINIMALLYINVASIVE ARTHROSCOPIC PROCEDURES (Attorney's Docket No.JORGEN-71999.63838).

The five (5) above-identified patent applications are herebyincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to surgical methods and apparatus in general, andmore particularly to methods and apparatus for performing arthroscopicprocedures, particularly arthroscopic procedures on the hip, includingarthroscopic diagnostic and surgical procedures.

BACKGROUND OF THE INVENTION

Access to the knee and/or shoulder joints during arthroscopic surgery istypically made through two portals, often referred to as the operativeportal and the visualization portal. An arthroscope is inserted throughthe visualization portal, while a surgical instrument is insertedthrough the operative portal. If desired, the role of the visualizationportal can be interchanged with the role of the operative portal toprovide better viewing of, and/or better access to, internal capsularstructures.

The hip is complex and difficult to access using arthroscopictechniques. FIGS. 1, 2A, 2B, 2C and 2D illustrate the basic anatomy ofthe hip. For the sake of simplification, FIGS. 1, 2A, 2B, 2C and 2D donot show the surrounding synovial membrane, the femoral ligamentcomplex, the adductor muscle structure, varying layers of fat, and othertissue, all of which compound the difficulty in accessing the jointcapsule. There are also many delicate structures surrounding the hipjoint that are not shown in FIGS. 1, 2A, 2B, 2C and 2D, e.g., theanterior femoral neurovascular bundle, the lateral femoral cutaneousnerve, the lateral femoral circumflex artery and the sciatic nerve,among others. Damage to these structures can be permanent andirreparable, so care must be taken to avoid harming these structuresduring surgery.

Typically, access to the hip joint for minimally invasive arthroscopicsurgery is achieved through two access cannulas which line theaforementioned operative portal and visualization portal. The two accesscannulas are typically positioned in the so-called posterolateral andanterolateral positions, which are located 1-2 cm above (superior) and1-2 cm on each side of the landmark greater trocanter (see FIG. 3).Typically, the arthroscope is disposed in the posterolateral positionand the surgical instrument (e.g., forceps, dissector, scissors,scalpel, punch, probe, powered shaver, manual graspers, electrocauterywand, etc.) is disposed in the anterolateral position. However, as notedabove, it is common to interchange this positioning in order to improvevisualization and/or access to the target site.

Despite the ability to interchange the positioning of the arthroscopeand surgical instrument, areas of the distended surfaces of the hipjoint are generally not able to be fully visualized. FIG. 3 shows onesuch “No See” zone. The regions of the hip joint which are notaccessible by straight and rigid surgical instruments is even larger dueto the anatomy of the hip joint and the fixed geometry of the surgicalinstruments. For example, if the target site is in a region that islocated on the far side of the femoral head, a third portal must oftenbe established in the so-called anterior position. However, thisanterior portal considerably increases the risk associated with theprocedure, due to the proximity of the third portal to the lateralfemoral cutaneous nerve, the lateral femoral circumflex artery and thefemoral neurovascular bundle. Unfortunately, access via the opposite,posterior side of the joint, i.e., via the gluteal region, is generallynot a viable option, nor is access via a medial approach from the groin.

Roughly half of the distended hip joint is inaccessible via the normal,accepted portal placement positions (i.e., the aforementionedposterolateral and anterolateral positions). While visualization can beimproved somewhat by physically “prying” the access cannulas into acontrived position, and/or by performing excessive capsulectomies,access remains a significant hurdle to the performance of arthroscopicprocedures on the hip.

The preferred solution would be to provide steerable surgicalinstruments that can enter the capsule of the hip joint in a straightconfiguration through any of the access portals commonly used (e.g., theaforementioned posterolateral and anterolateral portals), and then besteered into a “No See” zone, e.g., as depicted in FIG. 4. Preferably,this steerable surgical instrument would have a robust straight section120 and a steerable section 122 that is set to a straight configurationduring insertion into the capsule and is then steered into the operableposition through the manipulation of controls housed in an instrumenthandle positioned outside the capsule and connected to the proximal endof straight section 122.

SUMMARY OF THE INVENTION

This invention generally relates to methods and apparatus for performingarthroscopic procedures, particularly arthroscopic procedures on thehip. The methods and apparatus of the present invention provide accessto regions of the spherically-shaped hip joint that are inaccessibleusing current arthroscopic instrumentation.

The methods and apparatus of the present invention can be suitably usedto perform arthroscopic procedures not only on the hip joint, but alsoon other parts of the anatomy that require flexible access, e.g., theknee joint, the shoulder joint, etc. The methods and apparatus of thepresent invention are not limited to arthroscopy, and can further beused in endoscopic and laparoscopic procedures as well as in opensurgical procedures.

One form of the present invention generally relates to the provision anduse of a surgical instrument for diagnostic or surgical procedures,wherein the surgical instrument comprises:

a handle disposed at the proximal end of the surgical instrument;

an elongate outer tube having a proximal end and a distal end, theelongate outer tube extending distally from the handle;

a flexible, distal end segment extending from the distal end of theelongate outer tube;

an operable tip comprising an outer cutting window member and an innercutting member;

the outer cutting window member of the operable tip being rotatablymounted to the distal end of an inner extension tube, the innerextension tube having its proximal end connected to a rotation controlknob in the handle;

an actuation means for rotating the inner cutting member of the operabletip via a flexible actuating cable or a high-speed inner extension tube;

manipulation mechanisms at the proximal end of the surgical instrumentfor manipulating the disposition of the flexible distal end segment;

wherein the surgical instrument provides at least the followingindependent degrees of freedom: curvilinear bending of the flexibledistal end segment to provide the flexible distal end segment with anarcuate axis, rotation of the outer cutting window member of theoperable tip about the arcuate axis of the flexible distal end segment,and rotation of the inner cutting member of the operable tip relative tothe outer cutting window member of the operable tip.

In another form of the present invention, the invention generallycomprises the provision and use of a surgical instrument for performingdiagnostic and/or surgical procedures, the surgical instrumentcomprising:

a handle at the proximal end of the surgical instrument;

an operable tip rotatably mounted at the distal end of the surgicalinstrument, the operable tip comprising an outer cutting window memberand an inner cutting member;

a rigid elongated outer tube fixed relative to the handle andinterconnected with a flexible distal end segment;

the outer cutting window member of the operable tip connected to aninner extension tube;

a spring preloading means to bias the outer cutting window member intocontact with the flexible distal end segment;

a rotation control knob in the handle connected to the inner extensiontube;

the inner cutting member of the operable tip, preferably a high speedcutting element, being rotatably mounted at the distal end of a flexibleactuating cable or a high-speed inner extension tube;

flexion control means for bending the flexible distal end segment, theflexion control means comprising a bending cam and one or more pairs oftensioning members interconnecting the bending cam and the flexibledistal end segment, wherein manipulation of the bending cam places atensile force on one or more tensioning members and causes the flexibledistal end segment to bend proportionally to the tensile force, andwherein bending of the flexible distal end segment provides the flexibledistal end segment with an arcuate axis;

a rotation control knob in connection with the operable tip for rotatingthe outer cutting window member of the operative tip about the arcuateaxis of the flexible distal end segment; and

an external drive mechanism in flexible connection with the innercutting member of the operable tip, preferably a high-speed cuttingelement.

In another form of the invention, the outer cutting window member of theoperable tip is held in place relative to the flexible distal endsegment by the tensioning members in a manner that secures the outercutting window member relative to the flexible distal end segment and ina manner that allows the outer cutting window member to be rotatedbefore insertion into the joint by gripping the outer cutting windowmember directly and rotating it by hand to a desired position.

Embodiments according to these aspects of the invention can include thefollowing features.

The surgical instrument can be designed for use in medical proceduresperformed on the hip (e.g., arthroscopic procedures on the hip) and theflexible tensioning members, the inner extension tube and the flexibledistal end segment can take on a curved profile having a bend radiuscorresponding to the curvature of the femoral head. In some embodimentsof the present invention, the bend radius can be approximately 25 mm. Itshould also be appreciated that the present invention can also bedesigned for use in medical procedures on the knee or shoulder, and thebend radius can be less than 25 mm. In some embodiments of the presentinvention, the bend radius can be approximately 12 mm. The device can beconfigured for use in medical procedures on the elbow, wrist, orintraverterbral spaces, and the bend radius can be less than 12 mm. Insome embodiments, the bend radius can range from about 1 mm to about 5mm. The surgical instrument can be for use in general abdominallaparoscopy, and the bend radius can range from about 25 mm to about 50mm.

The flexible tensioning members, the inner extension tube and theflexible distal end segment preferably have a cylindrical shape with acircular cross-section. These elements can comprise a lightweight andstrong bio-compatible material. By way of example but not limitation,the material may comprise surgical grade stainless steel, anodizedaluminum, polymeric materials or composites. The materials of theflexible distal end segment can be chosen so as to provide excellentlubricious bearing properties for the support of a high-speed rotatinginner extension tube.

The operable end of the surgical instrument can comprise cylindricalelements rotationally movable relative to each other, and the surgicalinstrument can further include actuation or control mechanisms at itsproximal end.

A first actuation mechanism can comprise a control mechanism that canadapt to an external high-speed motor-driven handpiece via a flexiblebearing shaft (or drive cable) that drives the inner cutting member ofthe operable tip.

A second actuation mechanism can comprise a bending control mechanismwhich comprises a trigger, ring, or one or more actuating buttons on thehandle. The handle can be hollow and house apparatus that connects theactuation mechanism to the flexible distal end segment. The apparatusthat connects the bending control mechanism to the flexible distal endsegment can include one or more tensioning members such as cables orpush/pull rods or metal ribbons in connection with a bending cam thatcauses the flexible distal end segment to bend upon rotation of thebending cam.

A third control mechanism can provide the means to rotate the outercutting window member of the operable tip independent of the flexibledistal end segment. It can be rotatable about the arcuate axis of thenon-rotating outer distal end segment.

The present invention can articulate in any combination of the followingfive degrees of freedom, which are described in more detail herein: (i)translation along the axis of the tubular outer body member, resultingfrom the surgeon inserting or withdrawing the device from the body, (ii)curvilinear bending of a distal portion of the surgical instrument,(iii) rotation about the linear axis of the outer tube resulting fromthe surgeon rotating his/her wrist and hand, (iv) rotation of the outercutting window member of the operable tip relative to the outer tube,and (v) rotation of the inner cutting member of the operable tiprelative to the outer cutting window member.

The operable tip can be removable and interchangeable. The inner cuttingmember can be removable and interchangeable. The operable tip maycomprise a powered blade with suction, and the device can furthercomprise an actuation mechanism disposed at its proximal end. Thisactuation mechanism may comprise a flexible actuating cable that can beconnected to an external drive motor. Thus, tissue and other materialcan be pulled into the operable tip using suction and the tissue andother material can be resected and withdrawn through the device usingthe inner cutting member in combination with suction (e.g., byconnecting the surgical instrument to a vacuum source).

The entire surgical instrument, or one or more portions of the surgicalinstrument, such as the inner member, elongate member, and/or operableend, can be disposable.

The entire device, or one or more parts of the device, can be reusable.

In another aspect of the present invention, the invention generallyrelates to a medical device kit, comprising one or more of thecomponents set forth herein. The one or more surgical instruments can bepackaged in sterile condition.

In another aspect of the present invention, the invention generallyrelates to a method for performing minimally invasive diagnostic andsurgical procedures on the hip, the method comprising:

(a) providing an operable surgical instrument comprising a handledisposed at the proximal end; an operable tip disposed at the distalend; a rigid outer tube extending between the handle and the operabletip; a flexible distal end segment; an outer cutting window member ofthe operable tip being rotatably connected relative to the flexibledistal end segment; a flexible actuating cable to drive a high-speedinner cutting member of the operable tip; the handle comprising controlmeans to maneuver the operable tip by iteratively adjusting one or moreof the following degrees of freedom: linear translation of the operableend into the hip joint capsule, resulting from the surgeon inserting orwithdrawing the instrument from the body; rotation of the surgicalinstrument about the linear axis of the outer tube by rotating thehandle with a twisting motion of the wrist; curvilinear bending of theflexible distal end segment; rotation of the outer window cutting memberabout an arcuate axis of a bend in the flexible distal end segment; andhigh-speed rotation of the inner cutting member;

(b) configuring the flexible distal end segment into a straightconfiguration;

(c) inserting the distal end of the surgical instrument into the bodyand into the hip capsule;

(d) iteratively adjusting the curvilinear bend radius of the flexibledistal end segment while translating the operable tip toward theoperative target;

(e) rotating the outer cutting window member to face the surgicaltarget;

(f) actuating the high speed inner cutting member;

(g) performing the procedure;

(h) configuring the flexible distal end segment into a straightconfiguration; and

(i) removing the surgical instrument from the capsule.

In one preferred form of the present invention, there is provided asurgical instrument, said surgical instrument comprising:

a hollow shaft having a distal end and a proximal end;

a handle disposed at said proximal end of said hollow shaft;

a flexible distal end segment disposed at said distal end of said hollowshaft, said flexible distal end segment comprising a distal end and aproximal end, with said proximal end of said flexible distal end segmentbeing mounted to said distal end of said hollow shaft;

at least one tensioning member extending between said distal end of saidflexible distal end segment and said handle for manipulating said distalend of said flexible distal end segment relative to said hollow shaftwhereby to provide curvilinear bending of said flexible distal endsegment relative to said hollow shaft;

an outer cutting window member rotatably mounted to said distal end ofsaid flexible distal end segment;

an inner extension tube extending through said hollow shaft and saidflexible distal end segment for selectively rotating said outer cuttingwindow member relative to said flexible distal end segment, said innerextension tube having a distal end and a proximal end, said distal endof said inner extension tube being mounted to said outer cutting windowmember and said proximal end of said inner extension tube extending tosaid handle;

an inner cutting member rotatably disposed within said outer cuttingwindow member; and

a rotational element for rotating said inner cutting member relative tosaid outer cutting window member, said rotational element comprising adistal end connected to said inner cutting member and a proximal endextending to said handle;

wherein said surgical instrument is configured so as to provide at leastthe following independent degrees of freedom: curvilinear bending ofsaid flexible distal end segment relative to said flexible distal endsegment, rotation of said outer cutting window member relative to saidflexible distal end segment, and rotation of said inner cutting memberrelative to said outer cutting window member.

In another preferred form of the present invention, there is provided amethod for performing a procedure, said method comprising:

providing a surgical instrument, said surgical instrument comprising:

-   -   a hollow shaft having a distal end and a proximal end;    -   a handle disposed at said proximal end of said hollow shaft;    -   a flexible distal end segment disposed at said distal end of        said hollow shaft, said flexible distal end segment comprising a        distal end and a proximal end, with said proximal end of said        flexible distal end segment being mounted to said distal end of        said hollow shaft;    -   at least one tensioning member extending between said distal end        of said flexible distal end segment and said handle for        manipulating said distal end of said flexible distal end segment        relative to said hollow shaft whereby to provide curvilinear        bending of said flexible distal end segment relative to said        hollow shaft;    -   an outer cutting window member rotatably mounted to said distal        end of said flexible distal end segment;    -   an inner extension tube extending through said hollow shaft and        said flexible distal end segment for selectively rotating said        outer cutting window member relative to said flexible distal end        segment, said inner extension tube having a distal end and a        proximal end, said distal end of said inner extension tube being        mounted to said outer cutting window member and said proximal        end of said inner extension tube extending to said handle;    -   an inner cutting member rotatably disposed within said outer        cutting window member; and    -   a rotational element for rotating said inner cutting member        relative to said outer cutting window member, said rotational        element comprising a distal end connected to said inner cutting        member and a proximal end extending to said handle;    -   wherein said surgical instrument is configured so as to provide        at least the following independent degrees of freedom:        curvilinear bending of said flexible distal end segment relative        to said flexible distal end segment, rotation of said outer        cutting window member relative to said flexible distal end        segment, and rotation of said inner cutting member relative to        said outer cutting window member;

manipulating said handle so as to advance said outer cutting windowmember at a selected site; and

performing at least one of curvilinear bending of said flexible distalend segment relative to said flexible distal end segment, rotation ofsaid outer cutting window member relative to said flexible distal endsegment, and rotation of said inner cutting member relative to saidouter cutting window member.

In another preferred form of the present invention, there is provided asurgical instrument, said surgical instrument comprising:

a hollow shaft having a distal end and a proximal end;

a handle disposed at said proximal end of said hollow shaft;

a flexible distal end segment disposed at said distal end of said hollowshaft, said flexible distal end segment comprising a distal end and aproximal end, with said proximal end of said flexible distal end segmentbeing mounted to said distal end of said hollow shaft;

at least one tensioning member extending between said distal end of saidflexible distal end segment and said handle for manipulating said distalend of said flexible distal end segment relative to said hollow shaftwhereby to provide curvilinear bending of said flexible distal endsegment relative to said hollow shaft;

an outer cutting window member rotatably mounted to said distal end ofsaid flexible distal end segment;

an inner extension tube extending through said hollow shaft and saidflexible distal end segment for selectively rotating said outer cuttingwindow member relative to said flexible distal end segment, said innerextension tube having a distal end and a proximal end, said distal endof said inner extension tube being mounted to said outer cutting windowmember and said proximal end of said inner extension tube extending tosaid handle;

at least one spring for yieldably biasing said inner extension tubeproximally so as to yieldably bias said outer cutting window memberproximally against said distal end of said flexible distal end segment;

an inner cutting member rotatably disposed within said outer cuttingwindow member; and

a rotational element for rotating said inner cutting member relative tosaid outer cutting window member, said rotational element comprising adistal end connected to said inner cutting member and a proximal endextending to said handle;

wherein said surgical instrument is configured so as to provide at leastthe following independent degrees of freedom: curvilinear bending ofsaid flexible distal end segment relative to said flexible distal endsegment, rotation of said outer cutting window member relative to saidflexible distal end segment, and rotation of said inner cutting memberrelative to said outer cutting window member.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention, as well as the invention itself, will be more fullyunderstood from the following detailed description of the preferredembodiments, which is to be read together with the accompanyingdrawings, in which:

FIG. 1 is a schematic view showing a cross-sectional anterior view of adistended right hip joint;

FIG. 2A is a schematic view showing a posterior view of the right hipjoint;

FIG. 2B is a schematic view showing an anterior view of a right hipjoint with various ligaments shown;

FIG. 2C is a schematic view showing the anatomical structuressurrounding the right hip joint;

FIG. 2D is a schematic view showing a cross-sectional posterior view ofthe right hip joint;

FIG. 3 is a schematic view showing access to the hip joint using a “70degree” arthroscope and a rigid surgical instrument;

FIG. 4 is a schematic view showing access to the hip joint in accordancewith the present invention (i.e., using a steerable arthroscope and asteerable surgical instrument);

FIG. 5 is a schematic view showing a novel surgical instrument formed inaccordance with the present invention;

FIGS. 6A, 6B and 6C are schematic views showing various configurationsof the distal end of the novel surgical instrument shown in FIG. 5;

FIGS. 7A and 7B are schematic views showing a one-piece molded flexibledistal end segment which is utilized in the distal end of the novelsurgical instrument shown in FIG. 5;

FIG. 8 is a schematic view showing the handle of a first embodiment ofthe novel surgical instrument shown in FIG. 5;

FIGS. 8A and 8B are schematic views showing how the inner extension tubemay be spring biased proximally so as to keep the outer cutting windowmember biased against the flexible distal end segment;

FIG. 9 is a schematic view showing the distal end of the firstembodiment of the novel surgical instrument which uses the handle shownin FIG. 8;

FIGS. 10A, 10B and 10C are schematic views similar to the views of FIGS.6A, 6B and 6C, showing the distal end of the novel surgical instrumentcomprising a burr;

FIG. 11 is a schematic view showing the handle of a second embodiment ofthe novel surgical instrument shown in FIG. 5;

FIG. 12 is a schematic view showing the distal end of the secondembodiment of the novel surgical instrument which uses the handle shownin FIG. 11;

FIG. 13 is a schematic view showing the handle of a third embodiment ofthe novel surgical instrument shown in FIG. 5;

FIG. 14 is a schematic view showing the distal end of the thirdembodiment of the novel surgical instrument which uses the handle shownin FIG. 13; and

FIGS. 14A and 14B are schematic views showing constructions for thedistal end of the novel surgical instrument shown in FIGS. 13 and 14.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The methods and apparatus of the present invention are primarilyillustrated and described herein by means of surgical instruments whichhave been adapted for use in performing arthroscopic procedures on thehip. The methods and apparatus described herein provide access to theinternal portions of the distended hip capsule during arthroscopicprocedures that are presently not accessible using currently availablearthroscopic instruments. The methods and apparatus of the presentinvention can suitably be used to perform arthroscopic procedures notonly on the hip, but also on other parts of the body, such as the kneeand shoulder. The surgical instruments are particularly suitable forperforming procedures on parts of the body that require flexible access.The methods and apparatus of the present invention are not limited toarthroscopy, and can further be used in endoscopic and laparoscopicprocedures as well as open surgeries. The surgical instruments of thepresent invention can be in the general form of any conventionalsurgical instrument including, but not limited to, a tubulartissue-cutting device wherein the cutting element is disposed within anouter window element and can be rotated by means of a motor. Thus, thedisclosure to follow should be construed in an illustrative sense ratherthan in a limiting sense.

First Embodiment

In a first embodiment, with reference to FIGS. 5-10, an operable tip 405is independently rotatable relative to a flexible distal end segment 414which is fixed to the distal end of an outer tube 406. Operable end 405comprises an outer cutting window member 423 (FIG. 6A) comprising acutting window 423A and an inner cutting member 424 which togetherprovide a tissue cutting function when inner cutting member 424 isrotated relative to cutting window 423A. A handle 403 (FIG. 5) housesthe actuation means for controlling (i) the bending of flexible distalend segment 414 relative to outer tube 406 (and hence the disposition ofoperable end 405 relative to handle 403), (ii) the rotation of outercutting window member 423 relative to flexible distal end segment 414(and hence the disposition of cutting window 423A relative to handle403), and (iii) high-speed driver features which control rotation ofinner cutting member 424 relative to flexible distal end segment 414(and hence the rotation of inner cutting member 424 relative to outercutting window member 423).

(i) The bending of flexible distal end segment 414 relative to outertube 406 is achieved by the actuation of two diametrically-opposedtensioning members 421 (FIG. 8), which are connected to bending cam 411in handle 403 and extend through outer tube 406 and flexible distal endsegment 414, with tensioning members 421 being attached to the distalend of flexible distal end segment 414 (FIG. 6A). As bending cam 411 ispivoted within handle 403, it places one or the other of the tensioningmembers 421 in tension which, in turn, bends flexible distal end segment414 in one direction.

(ii) The rotation of outer cutting window member 423 of operable tip 405is controlled by the rotation of a rotation control knob 412 (FIG. 5)which is connected to an inner extension tube 431 (FIGS. 6A and 8) whichextends through outer tube 406 and flexible distal end segment 414 andis secured to outer cutting window member 423 of operable tip 405 (FIG.9). This rotation positions cutting window 423A in a desired rotationalposition relative to handle 403, e.g., for improved tissue access. Notethe difference in window position in the three views shown in FIGS. 6A,6B and 6C as rotation control knob 412 turns outer cutting window member423 (and hence turns cutting window 423A). In a first position shown inFIG. 6A, cutting window 423A is positioned on the inside of the bend arcof flexible distal end segment 414; in a second position shown in FIG.6B, cutting window 423A is positioned on the side of the bend arc offlexible distal end segment 414; and in a third position shown in FIG.6C, cutting window 423A is positioned on the outside of the bend arc offlexible distal end segment 414.

(iii) The actuation of operable tip 405 (i.e., the rotation of innercutting member 424 relative to flexible distal end segment 414, andhence the rotation of inner cutting member 424 relative to outer cuttingwindow member 423) is controlled by rotation of a bearing shaft 417(FIG. 5) and a flexible actuating cable 416 (FIGS. 6A and 8), withflexible actuating cable 416 being secured at its distal end to innercutting member 424 (FIG. 9). Bearing shaft 417 is designed to interfacewith an external drive motor (not shown). This actuation of bearingshaft 417 turns actuating cable 416 which turns inner cutting member 424within operable tip 405 (i.e., within outer cutting window member 423).Resected tissue from operable tip 405 is removed from the joint byapplying suction (from an external suction source) to a suction hosefitting 415. Inner cutting member 424 of operable tip 405 can havedifferent cutting characteristics for different surgical requirements.For example, the cutting of soft tissue generally requires that innercutting member 424 comprise a sharp edge, e.g., as shown FIGS. 6A, 6Band 6C. Bone, however, is generally resected using a burr that uses manysmall sharp ridges to grind the bone surface rather than attempting toslice it with a sharp edge, e.g., such as a burr 605 shown in FIGS. 10A,10B and 10C.

As discussed above, handle 403 houses the various means for controllingoperation of the distal end of the surgical instrument, i.e., thebending of flexible distal end segment 414 relative to the longitudinalaxis of outer tube 406, the rotation of outer cutting window member 423of operable tip 405 relative to flexible distal end segment 414, and thehigh-speed rotation of inner cutting member 424 relative to outercutting window member 423. Tension steering means (i.e., bending cam 411and tensioning members 421) are provided for controlling the bend radiusof flexible distal end segment 414. Tensioning members 421 are selectedto meet the requirements for stiffness and flexibility of flexibledistal end segment 414. Woven or braided cables generally provide thebest flexibility, and flat ribbons of stainless steel or Nitinolgenerally provide the best stiffness. Other materials and/orcross-sectional configurations are available for applications thatpresent other unique requirements. Tensioning members 421 terminatedistally on the most distal end of flexible distal end segment 414 (FIG.6A) and are controlled by bending cam 411 located in handle 403. As seenin FIG. 9, a circumferential groove 414A is provided in the distalmostvertebra 422 to contain a circumferential wrap of tensioning members421.

Flexible distal end segment 414 can be in the form of a single-piece,injection-molded plastic part (FIGS. 7A and 7B), made from materialschosen for the their bending fatigue resistance properties as well astheir lubricious bearing properties, e.g., urethane, nylon, PEEK, Teflonand the like. The configuration of flexible distal end segment 414preferably comprises a series of vertebra 422 interconnected bybeam-shaped webs 425. As the tension in one of tensioning members 421 isincreased, the vertebrae 422 surrounding that tensioning member movecloser together, thereby placing the beam-shaped webs 425 in a state ofbending. Webs 424 bend like a beam rather than a pivot. The stress isdistributed linearly over the distance between the neutral axis and thethickness of the beam. This improves the fatigue life of the beam-shapedwebs 424, by avoiding the stress riser point loads that are common witha pivotally-hinged geometry as opposed to a bending geometry. Flexibledistal end segment 414 can further comprise at least one axial hole 426through which inner extension tube 431 (FIG. 6A) can pass (for thepurpose of rotating outer cutting window member 423), as well as holesor slots 427 (shown in the 12 o'clock and 6 o'clock positions) forreceiving tensioning members 421.

Tensioning members 421 are routed around strategically-positionedbearings 421B and connected to bending cam 411 (FIG. 8) which can beconveniently positioned for rotation by the thumb or forefinger. Asbending cam 411 is rotated, one of the pair of tensioning members 421 isplaced into tension so as to bend flexible distal end segment 414 inproportion to the tension that is applied. The other tensioning member421 is slackened so as to extend over its elongated distance.

Rotation control knob 412 (FIGS. 5 and 8) can be rotated (e.g., inbearing saddles 413, FIG. 8) and can be conveniently disposed forrotation by a finger (e.g., the forefinger) or the thumb. Innerextension tube 431 (FIG. 6A) is secured to rotation control knob 412,such that when rotation control knob 412 is rotated, inner extensiontube 431 rotates as well, however, rotation control knob 412 ispreferably biased proximally (e.g., under the pulling force applied by apre-load spring 412A) so as to bias inner extension tube 431 proximally.The distal end of inner extension tube 431 is connected to the proximalend of outer cutting window member 423 (FIG. 9) of operable tip 405. Theproximal end of inner extension tube 431 can terminate in a housing 432(FIG. 8) which is sealed to the interior of handle 403 with seals 433(e.g., O-ring seals). Seals 433 are provided to hold the vacuum in avacuum chamber 444 while still permitting rotation of inner extensiontube 431 and housing 432. Vacuum chamber 444 is connected with anexternal vacuum source via suction hose fitting 415. As noted above, theproximal end of flexible actuating cable 416 (FIGS. 6A and 8) isconnected to bearing shaft 417. Bearing shaft 417 rotates in a shaftseal 418 (FIG. 8) which maintains the vacuum of vacuum chamber 444.Vacuum chamber 444 pulls fluid and resected tissue from operable tip405, through inner extension tube 431 and out of the surgical instrumentthrough suction hose fitting 415. To prevent tissue from clogging theinterior of inner extension tube 431, flexible actuating cable 416 canbe designed and disposed to rotate in a random, non-linear pattern so asto disrupt any tissue aggregation. This random, non-linear pattern canbe kept irregular by varying the rotational speed of actuating cable416. In this respect it will be appreciated that it is well known bythose skilled in the art that a high-speed driven cable seeksequilibrium by deflecting its shaft into a sinusoidal shape, theamplitude and period of which changes by changing the speed of rotationor by changing the distance between the supporting bearings at each endof the cable. By way of example but not limitation, flexible actuatingcable 416 can rotate within the limits of “straight on the center line”with low speed or in contact with the walls of inner extension tube 431with high speed. During bending of flexible distal end segment 414, thegeometry of the bend is such that the outer cutting window member 423extends slightly beyond the distal end of flexible distal end segment414 (as it compresses during bending) which can compromise the lateralbearing strength of operable tip 405. To compensate for this, therotation control knob 412 can be configured to (i) allow the innerextension tube 431 to translate axially in response to the pulling forceapplied by spring 412A, and (ii) rotationally secure the inner extensiontube 431 to rotation control knob 412 by means well known in the art(e.g., by engaging a hex-shaped feature, not shown, mounted to the outerdiameter of inner extension tube 431).

Thus, in one preferred form of the invention, and looking now at FIG. 8,rotation control knob 412 is spring biased proximally by spring 412A soas to spring bias inner extension tube 431 proximally, and hence tospring bias outer cutting window member 423 into contact with the distalend of flexible distal end segment 414.

Alternatively, other means may be provided for spring biasing innerextension tube 431 proximally so as to pull outer cutting window member423 proximally against the distal end of flexible distal end segment414.

By way of example but not limitation, and looking now at FIGS. 8, 8A and8B, inner extension tube 431 is sized and positioned so that whenflexible distal end segment 414 is bent, inner extension tube 431 isalso bent and conforms to the arc established by the inner passage offlexible distal end segment 414. This, in turn, will cause the flexibleactuating cable 416 to bend, as flexible actuating cable 416 alsoconforms to the inner passage of inner extension tube 431. Innerextension tube 431 is further configured so that when it is bent, itsdistal end engages surface 423A of outer cutting window member 423(FIGS. 8A and 8B) and its proximal end engages rotation control knob 412(see FIG. 8).

Inner extension tube 431 is further configured so that when the flexibledistal end segment 414 is in a straight, unbent configuration, the sidewall of inner extension tube 431 is in a relaxed state.

In one preferred form of the invention, at least the distal end of innerextension tube 431 may comprise coils, and when flexible distal endsegment 414 is in a straight, unbent configuration, the coils whichcomprise inner extension tube 431 are in a relaxed state in which thereis no space between the adjacent coils. As best seen in FIG. 8B, innerextension tube 431 is also configured so that when it is bent, aradially inward (with respect to the arc established by the bend)portion of each coil of inner extension tube 431 remains in contact witha radially inward portion of each adjacent coil. At the same time, aspace is introduced between a radially outward portion of each coil ofinner extension tube 431 and a radially outward portion of each adjacentcoil. In a particular embodiment, the coils of inner extension tube 431are substantially rectangular as illustrated in FIGS. 8A and 8B.

Tensioning members 421 may be used to bend flexible distal end segment414 so as to allow flexible distal end segment 414 to take on a desiredcurvature. The size and configuration of vertebrae 422 of flexibledistal end segment 414 provide structure so that flexible distal endsegment 414 may be selectively curved with relatively little force onthe tensioning members 421. The slidably disposed inner extension tube431 is forced by vertebrae 422 to adopt a conforming curvature.

As discussed above, in order to prevent the protrusion of innerextension tube 431 from the distal end of flexible distal end segment414 during bending of flexible distal end segment 414, the spring 412Amay be provided in handle 403 for biasing inner extension tube 431proximally. Alternatively, and/or additionally, a spring 412B (FIGS. 8Aand 8B) may be provided within outer tube 406, near the distal end ofouter tube 406, whereby to bias inner extension tube 431 proximallyrelative to outer tube 406 (and hence bias inner extension tube 431proximally relative to flexible distal end segment 414). By virtue ofthis construction, spring 412B biases inner extension tube 431 (andhence outer cutting window member 423) proximally so as to ensure thatwhen the flexible distal end segment 414 is bent, outer cutting windowmember 423 remains in contact with the distal end of the flexible distalend segment 414. As a result of the biasing force provided by spring412A (and/or by spring 412B), the proximal end of inner extension tube431 is forced to move in the proximal direction such that the “excesslength” of inner extension tube 431 (which occurs when flexible distalend segment 414 is bent) is drawn into outer tube 406.

As shown in FIGS. 8A and 8B, spring 412B is preferably disposedcircumferentially around inner extension tube 431 within the interior ofouter tube 406. Outer tube 406 is preferably formed with an inwardlyextending tab 434 (or other stopping mechanism) that engages the distalend of spring 412B, and inner extension tube 431 is preferably formedwith an outwardly extending circumferential flange 435 (or otherstopping structure) for engaging the proximal end of the spring 412B. Asshown in FIG. 8A, when flexible distal end segment 414 is in an uncurvedconfiguration, the spring 412B is in a relatively compressed state. Asshown in FIG. 8B, when flexible distal end segment 414 is curved, theeffective length of inner extension tube 431 is greater than theeffective length of flexible distal end segment 414. However, thebiasing force of spring 412B acting on inner extension tube 431 keepsouter cutting window member 423 in contact with the flexible distal endsegment 414 and causes the inner extension tube 431 to be withdrawn inthe proximal direction.

It will be understood that the biasing mechanisms discussed above (i.e.,springs 412A and/or 412B) are not limited to use in conjunction with thevertebrate flexible members of the illustrated embodiment, but could beused in conjunction with any elongate surgical instrument embodiment ofthe invention that has a curvable end segment with two coaxiallydisposed flexible members having different lengths when the curvable endsegment is curved.

Flexible actuating cable 416 is secured at its distal end to innercutting member 424 of operable tip 405 as shown in FIG. 9. Inner cuttingmember 424 rotates freely within outer cutting window member 423. Tissueis resected as it is drawn into cutting window 423A and is engaged byinner cutting member 424. By way of example but not limitation, whereinner cutting member 424 comprises a windowed structure having cuttingedges, tissue is excised as the cutting edges of inner cutting member424 sweep across cutting window 423A (FIGS. 6A, 6B, 6C and 9). By way offurther example but not limitation, where inner cutting member 424comprises a burr, tissue is excised as tissue is engaged by the burr(FIGS. 10A, 10B and 10C). Inner extension tube 431 is designed to form aclose sliding fit with flexible distal end segment 414, such thatflexible distal end segment 414 serves as a rotational bearing surfacefor inner extension tube 431, and the material comprising flexible endsegment 414 is selected for the required bearing frictioncharacteristics. The most distal face of flexible distal end segment 414(i.e., the portion 414A of flexible distal end segment 414 that is incontact with surface 423A of outer cutting window member 423) is also athrust bearing surface.

Thus it will be seen that in accordance with the present invention,there is provided a novel steerable surgical instrument 5 whichgenerally comprises an outer tube 406, a flexible distal end segment 414secured to the distal end of outer tube 406, and a handle 403 secured tothe proximal end of outer tube 406. Flexible distal end segment 414comprises a flexible structure formed from a plurality of vertebra 422interconnected by beam-shaped webs 425.

Tensioning members 421 extend between bending cam 411 in handle 403 andthe distal end of flexible distal end segment 414, such that bending cam411 controls bending of the distal tip of flexible distal end segment414. Tensioning members 421 extend through holes 427 in vertebrae 422 inflexible distal end segment 414.

Outer cutting window member 423 is movably mounted to the distal end offlexible distal end segment 414. Inner extension tube 431 extendsbetween rotation control knob 412 in handle 403 and outer cutting windowmember 423, such that rotation control knob 412 controls the rotationaldisposition of outer cutting window member 423 (and hence the rotationaldisposition of cutting window 423A). Inner extension tube 431 extendsthrough axial hole 426 in vertebrae 422 in flexible distal end segment414.

Inner cutting member 424 is movably disposed within outer cutting windowmember 423. Flexible actuating cable 416 extends between bearing shaft417 (which is attachable to a drive motor) and inner cutting member 424,such that rotation of bearing shaft 417 causes rotation of inner cuttingmember 424 within outer cutting window member 423, whereby to cuttissue. Flexible actuating cable 416 extends through inner extensiontube 431.

Thus it will be seen that (i) bending cam 411 in handle 403 controlsbending of flexible distal end segment 414 (and hence the bendingdisposition of operable tip 405 relative to handle 403), (ii) rotationcontrol knob 412 in handle 403 controls the rotational disposition ofouter cutting window member 423 (and hence the rotational disposition ofcutting window 423A relative to handle 403), and (iii) rotation ofbearing shaft 417 controls rotation of inner cutting member 424 (andhence cutting action at cutting window 423A).

Suction hose fitting 415 allows suction to be applied to the interior ofnovel steerable surgical instrument 5, such that tissue cut by operabletip 405 can be removed from the surgical site.

Second Embodiment

In a second embodiment of the present invention, and looking now atFIGS. 11 and 12, flexible actuating cable 416 is replaced by ahigh-speed inner extension tube 445 that is secured at its distal end toinner cutting member 424 and is secured at its proximal end to bearingshaft 417. High-speed inner extension tube 445 provides a rotatingwindow 446 which is open to vacuum chamber 444. As a result, tissueresected into inner cutting member 424 is withdrawn by vacuum intovacuum chamber 444 via the lumen of high speed inner extension tube 445,where it is evacuated via suction hose fitting 415. Note that in thisform of the invention, sealed housing 432 is preferably joined withbearing shaft 417 such that sealed housing 432 and bearing shaft 417serve as rotating seals to preserve the vacuum in vacuum chamber 444.

Third Embodiment

In a third embodiment of the present invention, and looking now at FIGS.13 and 14, the aforementioned rotation control knob 412 is omitted. Moreparticularly, in this form of the invention, outer cutting window member423 is rotationally connected to flexible distal end segment 414 in amanner that allows the surgeon to rotate outer cutting window member 423by hand before inserting the distal end of the surgical instrument intothe joint. It is secured axially via molded retaining ring 414B (FIG.14A). The last-set position of outer cutting window member 423 remainsstatic throughout the surgical procedure (or until the surgeon choosesto withdraw the distal end of the surgical instrument from the joint andreposition outer cutting window member 423). To accommodate the snap-fitfeature of the outer cutting window member 423 to the molded retainingring feature 414B, the tensioning member 421 is fashioned as a flat ring421A as shown in FIG. 14B such that the flat ring is secured in thecircumferential molded recess 414A in the most distal vertebra. Withthis embodiment of the present invention, the aforementioned innerextension tube 431 is replaced by inner tubular drive shaft 447 whichhas its distal end connected to inner cutting member 424 instead of toouter cutting window member 423 (as is the case with the aforementionedfirst and second embodiments). In this form of the invention, innertubular drive shaft 447 serves to rotate inner cutting member 424 ofoperable tip 405. The proximal end of inner tubular drive shaft 447 isjoined to sealed housing 432 which is, in turn, fixed to bearing shaft417. Thus, turning bearing shaft 417 (e.g., with a drive motor) turnssealed housing 432, which turns inner extension tube 447, which turnsinner cutting member 424. A vacuum window 446 is provided in both innertubular drive shaft 447 and sealed housing 432 for providing fluidcommunication between operable tip 405 and vacuum chamber 444.

ADDITIONAL ASPECTS OF THE INVENTION

For each of the embodiments of the present invention, some or all of thesurgical instrument can be reusable. Alternatively some or all of thesurgical instrument can be disposable. In some embodiments of thepresent invention, removable and/or interchangeable distal ends,inner/outer body member(s), and/or elongate body members can be providedthat are reusable or disposable, as desired.

The present invention also comprises methods for performing arthroscopicprocedures using the embodiments discussed above so as to access theentire joint, with or without switching cannulated access portals. Thesemethods are performed using embodiments of the present invention thatflexibly move within the surgical field by bending flexible distal endsegment 414, rotating outer cutting window member 423 of operable tip405, and rotating inner cutting member 424. Thus, it will be appreciatedthat the present invention is capable of accessing the entire distendedcapsule volume of the joint and eliminating any “No See” zones withinthe surgical field. The present invention may also obviate the need forinserting the surgical instrument into more than one access portal inorder to allow for the access of the entire joint.

In another embodiment of the present invention, the invention generallyrelates to a method for performing minimally-invasive hip arthroscopicsurgical procedures by providing a surgical instrument comprising ahandle at the proximal end, a flexible or curvable portion at the distalend, and an elongate body member extending therebetween. An operable tipis rotatably mounted at the distal end. The bend radius of the flexibleor curvable portion can be controlled with at least one bendingtensioning member (e.g., at least one flexible cable) in the flexibledistal end segment, and can be tensioned by rotation of a cam-likeactuator located in the handle so as to achieve the desired bend radius.In each instance, the user can iteratively adjust the degree of bendingto accurately position the operable tip in the joint. The method of thepresent invention further comprises (i) positioning the flexible (orcurvable) distal portion into a straight configuration by tensioning asystem of opposing tensioning members until the flexible (or curvable)distal end segment is straight; (ii) inserting the straight elongatemember into the hip capsule; (iii) iteratively adjusting the bend radiusto position the operable tip in the desired arcuate position through themanipulation of control mechanisms in the handle; (iv) iterativelyadjusting the degree of rotation about the linear axis of the elongatedbody member; (v) adjusting the rotational position of the outer cuttingwindow member of the operable tip about its arcuate axis to the desiredrotational orientation using control mechanisms in the handle; (vi)performing the intended procedure by rotating the inner cutting memberof the operable tip (e.g., by connecting the inner cutting element to anexternal, hand-held motorized device); (vii) re-establishing thestraight configuration of the flexible distal end segment; and (viii)removing the device from the body.

Methods in accordance with the foregoing aspects of the presentinvention can further comprise multiple surgical instruments. By way ofexample but not limitation, after the visualization portal has beenestablished, it may be necessary to use one surgical instrument toresect tissue (e.g., a punch), a second surgical instrument to removetissue and loose bodies, a third surgical instrument to cauterize anyremaining bleeding sites, etc.

The present invention also comprises kits (not shown) that comprise oneor more surgical instruments formed in accordance with the presentinvention and packaged in sterile condition. Such kits also may includeone or more interchangeable operable tips, rigid and flexible tubularinterconnecting body members for use with the portions of the surgicalinstrument that may be reusable. In some embodiments, the kit includesflexible and/or rigid access cannulas that are sealed against the salinedistension pressure established within the joint capsule and insertedusing “safe access” trocars, mechanical flexation device(s) thatmechanically distend the hip joint laterally as well as longitudinallyalong the line of action coincident with the center line of the femoralneck, and fluid management systems to control the flow and pressure ofthe saline in the hip capsule.

The foregoing description of the invention is intended to be merelyillustrative thereof, and it will be appreciated that variations andmodifications can be effected without departing from the scope or spiritof the invention as set forth in the following claims. By way of examplebut not limitation, the bend-and-rotate approach for the precisedelivery of a multiplicity of operable tips provides significant utilitybeyond the hip applications described herein, (e.g., knee and shoulderarthroscopy, as well as smaller joint arthroscopy). The smaller diameterof the surgical instrument, as well as the flexibility of the surgicalinstrument, also makes it useful for other applications that requiredelicate tissue manipulation including, but not limited to, laparoscopiccholecystectomies, appendectomies, hernia repair, bariatric gastricby-pass, and certain thoracic and spinal procedures.

What is claimed is:
 1. A surgical instrument, said surgical instrumentcomprising: a hollow shaft having a distal end and a proximal end; ahandle disposed at said proximal end of said hollow shaft; a flexibledistal end segment disposed at said distal end of said hollow shaft,said flexible distal end segment comprising a distal end and a proximalend, with said proximal end of said flexible distal end segment beingmounted to said distal end of said hollow shaft; at least one tensioningmember extending between said distal end of said flexible distal endsegment and said handle for manipulating said distal end of saidflexible distal end segment relative to said hollow shaft whereby toprovide curvilinear bending of said flexible distal end segment relativeto said hollow shaft; an outer cutting window member rotatably mountedto said distal end of said flexible distal end segment; an innerextension tube extending through said hollow shaft and said flexibledistal end segment for selectively rotating said outer cutting windowmember relative to said flexible distal end segment, said innerextension tube having a distal end and a proximal end, said distal endof said inner extension tube being mounted to said outer cutting windowmember and said proximal end of said inner extension tube extending tosaid handle; an inner cutting member rotatably disposed within saidouter cutting window member; and a rotational element for rotating saidinner cutting member relative to said outer cutting window member, saidrotational element comprising a distal end connected to said innercutting member and a proximal end extending to said handle; wherein saidsurgical instrument is configured so as to provide at least thefollowing independent degrees of freedom: curvilinear bending of saidflexible distal end segment relative to said flexible distal endsegment, rotation of said outer cutting window member relative to saidflexible distal end segment, and rotation of said inner cutting memberrelative to said outer cutting window member.
 2. A surgical instrumentaccording to claim 1 wherein said flexible distal end segment comprisesa plurality of vertebrae which are interconnected with one another by atleast one web.
 3. A surgical instrument according to claim 2 whereinsaid at least one web deflects in the manner of a beam when subjected tobending forces.
 4. A surgical instrument according to claim 2 whereinsaid plurality of vertebrae are interconnected with one another by twowebs.
 5. A surgical instrument according to claim 4 wherein said twowebs are diametrically opposed from one another.
 6. A surgicalinstrument according to claim 2 wherein said flexible distal end segmentcomprises a single, integral piece.
 7. A surgical instrument accordingto claim 1 wherein said flexible distal end segment comprises at leastone opening extending therethrough, and further wherein said at leastone tensioning member extends through said at least one opening.
 8. Asurgical instrument according to claim 1 wherein said flexible distalend segment comprises at least one passageway extending therethrough,and further wherein said inner extension tube extends through said atleast one passageway.
 9. A surgical instrument according to claim 1wherein said at least one tensioning member comprises two tensioningmembers.
 10. A surgical instrument according to claim 9 wherein said twotensioning members each comprise a distal end and a proximal end, andfurther wherein said distal ends of said two tensioning members aresecured to said distal end of said flexible distal end segment and saidproximal ends of said two tensioning members extend to said handle. 11.A surgical instrument according to claim 9 wherein said two tensioningmembers are diametrically opposed from one another as they extend alongsaid flexible distal end segment and said hollow shaft.
 12. A surgicalinstrument according to claim 9 further comprising a bending cam mountedto said handle for selectively applying tension to said two tensioningmembers, and further wherein said proximal ends of said two tensioningmembers are secured to said bending cam.
 13. A surgical instrumentaccording to claim 1 further comprising a rotation control knob movablymounted to said handle, said proximal end of said inner extension tubebeing mounted to said rotation control knob.
 14. A surgical instrumentaccording to claim 13 wherein said rotational element comprises aflexible actuating cable.
 15. A surgical instrument according to claim13 wherein said rotational element comprises a high-speed innerextension tube.
 16. A surgical instrument according to claim 13 whereinsaid proximal end of said rotational element is configured for couplingto a drive motor.
 17. A method for performing a procedure, said methodcomprising: providing a surgical instrument, said surgical instrumentcomprising: a hollow shaft having a distal end and a proximal end; ahandle disposed at said proximal end of said hollow shaft; a flexibledistal end segment disposed at said distal end of said hollow shaft,said flexible distal end segment comprising a distal end and a proximalend, with said proximal end of said flexible distal end segment beingmounted to said distal end of said hollow shaft; at least one tensioningmember extending between said distal end of said flexible distal endsegment and said handle for manipulating said distal end of saidflexible distal end segment relative to said hollow shaft whereby toprovide curvilinear bending of said flexible distal end segment relativeto said hollow shaft; an outer cutting window member rotatably mountedto said distal end of said flexible distal end segment; an innerextension tube extending through said hollow shaft and said flexibledistal end segment for selectively rotating said outer cutting windowmember relative to said flexible distal end segment, said innerextension tube having a distal end and a proximal end, said distal endof said inner extension tube being mounted to said outer cutting windowmember and said proximal end of said inner extension tube extending tosaid handle; an inner cutting member rotatably disposed within saidouter cutting window member; and a rotational element for rotating saidinner cutting member relative to said outer cutting window member, saidrotational element comprising a distal end connected to said innercutting member and a proximal end extending to said handle; wherein saidsurgical instrument is configured so as to provide at least thefollowing independent degrees of freedom: curvilinear bending of saidflexible distal end segment relative to said flexible distal endsegment, rotation of said outer cutting window member relative to saidflexible distal end segment, and rotation of said inner cutting memberrelative to said outer cutting window member; manipulating said handleso as to advance said outer cutting window member at a selected site;and performing at least one of curvilinear bending of said flexibledistal end segment relative to said flexible distal end segment,rotation of said outer cutting window member relative to said flexibledistal end segment, and rotation of said inner cutting member relativeto said outer cutting window member.
 18. A method according to claim 17further comprising, before manipulating said handle so as to advancesaid outer cutting window member at a selected site, manipulating saidat least one tensioning member so as to cause said flexible distal endsegment to assume a substantially straight configuration.
 19. A methodaccording to claim 17 further comprising, after performing at least oneof curvilinear bending of said flexible distal end segment relative tosaid flexible distal end segment, rotation of said outer cutting windowmember relative to said flexible distal end segment, and rotation ofsaid inner cutting member relative to said outer cutting window member,manipulating said handle so as to withdraw said outer cutting windowmember from said selected site.
 20. A method according to claim 17further comprising, prior to manipulating said handle so as to withdrawsaid outer cutting window member from said selected site, manipulatingsaid at least one tensioning member so as to cause said flexible distalend segment to assume a substantially straight configuration.
 21. Amethod according to claim 17 wherein said flexible distal end segmentcomprises a plurality of vertebrae which are interconnected with oneanother by at least one web.
 22. A method according to claim 21 whereinsaid at least one web deflects in the manner of a beam when subjected tobending forces.
 23. A method according to claim 22 wherein saidplurality of vertebrae are interconnected with one another by two webs.24. A method according to claim 23 wherein said two webs arediametrically opposed from one another.
 25. A method according to claim21 wherein said flexible distal end segment comprises a single, integralpiece.
 26. A method according to claim 17 wherein said flexible distalend segment comprises at least one opening extending therethrough, andfurther wherein said at least one tensioning member extends through saidat least one opening.
 27. A method according to claim 17 wherein saidflexible distal end segment comprises at least one passageway extendingtherethrough, and further wherein said inner extension tube extendsthrough said at least one passageway.
 28. A method according to claim 17wherein said at least one tensioning member comprises two tensioningmembers.
 29. A method according to claim 28 wherein said two tensioningmembers each comprise a distal end and a proximal end, and furtherwherein said distal ends of said two tensioning members are secured tosaid distal end of said flexible distal end segment and said proximalends of said two tensioning members extend to said handle.
 30. A methodaccording to claim 28 wherein said two tensioning members arediametrically opposed from one another as they extend along saidflexible distal end segment and said hollow shaft.
 31. A methodaccording to claim 28 further comprising a bending cam mounted to saidhandle for selectively applying tension to said two tensioning members,and further wherein said proximal ends of said two tensioning membersare secured to said bending cam.
 32. A method according to claim 17further comprising a rotation control knob movably mounted to saidhandle, said proximal end of said inner extension tube being mounted tosaid rotation control knob.
 33. A method according to claim 32 whereinsaid rotational element comprises a flexible actuating cable.
 34. Amethod according to claim 33 wherein said rotational element comprises ahigh-speed inner extension tube.
 35. A method according to claim 33wherein said proximal end of said rotational element is configured forcoupling to a drive motor.
 36. A surgical instrument, said surgicalinstrument comprising: a hollow shaft having a distal end and a proximalend; a handle disposed at said proximal end of said hollow shaft; aflexible distal end segment disposed at said distal end of said hollowshaft, said flexible distal end segment comprising a distal end and aproximal end, with said proximal end of said flexible distal end segmentbeing mounted to said distal end of said hollow shaft; at least onetensioning member extending between said distal end of said flexibledistal end segment and said handle for manipulating said distal end ofsaid flexible distal end segment relative to said hollow shaft wherebyto provide curvilinear bending of said flexible distal end segmentrelative to said hollow shaft; an outer cutting window member rotatablymounted to said distal end of said flexible distal end segment; an innerextension tube extending through said hollow shaft and said flexibledistal end segment for selectively rotating said outer cutting windowmember relative to said flexible distal end segment, said innerextension tube having a distal end and a proximal end, said distal endof said inner extension tube being mounted to said outer cutting windowmember and said proximal end of said inner extension tube extending tosaid handle; at least one spring for yieldably biasing said innerextension tube proximally so as to yieldably bias said outer cuttingwindow member proximally against said distal end of said flexible distalend segment; an inner cutting member rotatably disposed within saidouter cutting window member; and a rotational element for rotating saidinner cutting member relative to said outer cutting window member, saidrotational element comprising a distal end connected to said innercutting member and a proximal end extending to said handle; wherein saidsurgical instrument is configured so as to provide at least thefollowing independent degrees of freedom: curvilinear bending of saidflexible distal end segment relative to said flexible distal endsegment, rotation of said outer cutting window member relative to saidflexible distal end segment, and rotation of said inner cutting memberrelative to said outer cutting window member.
 37. A surgical instrumentaccording to claim 36 wherein said at least one spring is disposed atsaid proximal end of said hollow shaft.
 38. A surgical instrumentaccording to claim 37 wherein said handle comprises a rotation controlknob mounted to said proximal end of said inner extension tube, whereinsaid rotation control knob can be used to selectively rotate said outercutting window member relative to said flexible distal end segment, andfurther wherein said at least one spring is mounted to said rotationcontrol knob so as to yieldably bias said rotation control knobproximally, whereby to yieldably bias said inner extension tubeproximally, whereby to yieldably bias said outer cutting window memberproximally against said distal end of said flexible distal end segment.39. A surgical instrument according to claim 36 wherein said at leastone spring is disposed at said distal end of said hollow shaft.
 40. Asurgical instrument according to claim 39 wherein said hollow shaftcomprises an inner flange, said inner extension tube comprises an outerflange, and further wherein said at least one spring is disposed betweensaid inner flange of said hollow shaft and said outer flange of saidinner extension tube so as to yieldably bias said inner extension tubeproximally relative to said hollow shaft, whereby to yieldably bias saidouter cutting window member proximally against said distal end of saidflexible distal end segment.